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I live in South Dakota. So, I can go from 75°F (24°C) with moderate humidity (indoors) to 0°F (-18°C) and dry just by stepping outside. Can this damage my lenses?

I especially want to know about damage to its optical performance, due to crazing or changes in alignment, or anything else - such as condensation leading to fungus. And I'm including damage to the lens coating. But I'm also curious about other damage. For example, if it shifts the housing clearance and allows more dust to get in, which could impact the image quality.

And if it can cause damage, then what parameters should I stay within to prevent damage (duration of exposure, temperature, humidity, etc.)? And does it make a difference if the lens housing is plastic or metal?

There are several separate issues involved with your question. Let's look at each in turn.

Sudden temperature changes

When materials are subjected to sudden temperature changes they can tolerate the change or can be irreversibly damaged. It all depends on the materials involved, the temperature extremes involved, and just how rapid the change is. Take any lens element heated to something like 300-400°F and drop it into a bucket of ice water and it will most likely crack. That doesn't mean walking out of your 75°F house into 0°F winter will have the same effect. In fact, it almost certainly will not.

Although 0°F is a little extreme, moving from room temperature to outside where the temperature is just below freezing doesn't seem to permanently harm cameras and lenses. What it does do is affect the battery that powers the camera (more on that in a bit). When ideal optical performance is required in cold weather, such as for astrophotography, allowing all of the optical components to stabilize at the ambient temperature before starting to shoot will avoid temporary minor optical issues due to different parts of the lens/camera cooling at different rates.

Moving from warm to cold environments is usually a lot easier on camera gear, in terms of long term health, than the opposite. The primary culprit is humidity.

Humidity and condensation

Condensation and moisture can damage your camera and lenses in several ways.

• Moisture can affect the electronics, particularly if a circuit is powered while wet. Allowing voltage to be applied to a circuit board while it is wet is a recipe for disaster. It will very often fry the electronics instantly.


• Condensation can leave mineral deposits behind on optical surfaces when it dries. It can also "weld" dust to lens elements or the camera's sensor and filter stack immediately in front of the sensor.


• If moisture is combined with a warm and dark environment, it can result in fungus growing inside the lens or camera. Keep in mind that fungus spores spread via air and are everywhere. So is dust. Even brand new lenses have dust in them. Those brand new lenses also probably have fungus spores in them. It's a biological fact of life when present in the Earth's atmosphere.

The most common cause of condensation on camera gear is caused by moving a cold camera and/or lens into a warm, humid environment. If the temperature of the camera or lens is below the dew point of the surrounding air, water droplets will condense on the cooler surfaces. This should be avoided as much as possible.

The easiest way to avoid condensation is to always put the camera/lens into a sealed bag before moving it from a cold to warm environment. The cold air sealed into the bag will contain less moisture than the warm air inside buildings. Leave the bag closed until the contents have warmed to room temperature. Any condensation that forms will do so on the exterior of the bag.

Cold and Batteries

Batteries are chemical devices that depend on chemical reactions to supply electricity. Those chemical reactions are affected by temperature. When batteries get very cold, their voltage drops rapidly. A battery that will power your camera for hundreds of shots at room temperature might only manage a few dozen frames in sub-freezing weather. The good news is that just warming the battery up restores some of its energy. If shooting in cold weather, carry plenty of spare batteries. Keep them warm inside your clothing. Swap the batteries in your camera and the warm batteries inside your clothes often.

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I've lived in Canada for a long time now. And my Nikon lenses have always been fine going from a comfy 25 degrees to minus 40 in a matter of minutes. Apart from some lens misting which I need to wipe sometimes, they've been impeccable.

Changing environments, especially those that are as extreme the ones you describe, can damage your equipment for reasons you've already described within your question.

• Different materials react to temperatures differently. This includes expansion, contraction, and changes in brittleness.


• Warmth and humidity are favorable to fungus.


• Water can condense and freeze on lenses, making them unusable.


• Etc.

To prevent such problems:

• Check your equipment documentation for acceptable operating parameters.




• Keep your equipment in an insulated enclosure when changing environments so they can acclimate gradually. The more extreme the temperature change, the more time you should allow for acclimation. This applies to blistering heat as well as to freezing temperatures.




• Consider using weather-resistant cameras and lenses that are designed to work in extreme environments. Consider using a "tough" compact camera.




• Limit the number and frequency of extreme environment changes. For instance, rather than bringing your equipment indoors for only a short time before returning outside, keep your equipment in a locker outside.

See also:

• What are these clusters of branching structures on/in my lens?

Your lens and camera do not go from 75F to 0F immediately due to the thermal inertia of the lens components and because air, in itself, is not a very good thermal conductor.

Moreover, pro-lens manufacturers use materials that have a very low coefficients of expansion. If I were you I would not worry about sudden contractions or expansion, because they don’t happen and since they don’t happen and the very low coefficient of expansion of the different materials won’t lead to misalignment in pro-lenses. But if you wish you can let the low temperature settle to all components of the lens, which means waiting for a long while as they reduce their temperature to 0F, if you think you need critical accuracy.

But on the other hand, condensation inside the lenses could be a problem due to the electronic that most modern lenses have and fungus proliferation.

If the lens isn’t airtight, when you move it form a place where it has stayed for a long while that has warm temperature and a high absolute humidity to a place with a much lower temperature and lower absolute humidity, this will be the physic phenomena that'll occur:

1. The air within the lens will still be the one it got before with
   the same humidity.


2. Its temperature will fall relatively fast (due to the low thermal
   inertia of the air).


3. The air trapped will get below its dew point and its humidity will
   start to condensate (became liquid).


4. You will end up with dew inside your lens.

But on the other hand your climate must already be very dry (relative and absolute humidity) during the cold season and I don’t think you are increasing the absolute humidity of your “house” by much. If you were increasing the absolute humidity by a lot, you should get a dehumidifier for your equipment closet to avoid the physical phenomena explained before.

A similar thing will happen when you go back inside from the freezing cold, if you have been outside for a while, the dew will occur on the outside of your equipment (notice the fogging of the glass in its outside). This is due to the fact that the low temperature of your equipment is lowering the temperature of the air surrounding it below its dew point. Inside the lens the outside air will raise its temperature but won’t generate any dew because it won’t become saturated.